The ore deposits of Utah . entering material. To what extent stop- SAN FRANCISCO AND ADJACENT DISTRICTS. 513 ing (the engulfment, sinking, and dissolvingof the invaded rock) provided space for theentering material is not definitely known, butthe writer is inchned to the view that itseffect was of minor importance, as Boutwellbelieves it to have been in the Park City dis-trict. FAULTS. The most important structural features ofthe region are the result of faulting. Normalfaulting is usually associated with the Basin association with other stocks. In the Stardistrict there has been movement along
The ore deposits of Utah . entering material. To what extent stop- SAN FRANCISCO AND ADJACENT DISTRICTS. 513 ing (the engulfment, sinking, and dissolvingof the invaded rock) provided space for theentering material is not definitely known, butthe writer is inchned to the view that itseffect was of minor importance, as Boutwellbelieves it to have been in the Park City dis-trict. FAULTS. The most important structural features ofthe region are the result of faulting. Normalfaulting is usually associated with the Basin association with other stocks. In the Stardistrict there has been movement along planesthat are essentially horizontal but that haveirregularities resembling a warped rocks along the fault pianos are highlypolished and grooved, but it is not demon-strated that there has been extensive move-ment. Faulting has probably been in progress overa long period. Some important faults doubt-less formed before the intrusion of the quartz .Supposed outline of part of originaltau It block before erosion. Figure 53.—Generalized stereogram representing the relations of the formations in part of the San Francisco Range north of Squaw Springs Pass. Range structure and is believed to outline theSan Francisco Range both on the east andwest. A fault on the east, exposed in theworkings of the Horn Silver mine, has a knowTidisplacement of 1,600 feet and doubtless muchmore. (See fig. 53.) Another notable normalfault passes northeast through Squaw SpringsGap in the San Francisco Range and throwsthe lavas on the south of the range downagainst the limestone on the north. The intrusion of the quartz monzonitebodies is believed to have laterally displacedthe surrounding rocks. Such a displacementis shown in the central portion of the Stardistrict, and similar displacements are pos-sibly present, though less clearly shown in > Boutwell, J. M., Stratigraphy and structure of the Park City , Utah: Jour. Geology, vol. 15, p. 458,1907 35416°—19 33 monzonit
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